Lieutenant Tang
Lieutenant Tang
Goes well with:
FAQs Answers to the most common questions.
How large does a Lieutenant Tang (Acanthurus tennenti) actually get in home aquariums, and what is the realistic minimum tank size for long‑term success?
Lieutenant Tangs reach 9–10 inches (23–25 cm) in captivity, with a deep, tall body that needs significant horizontal swimming room. While juveniles are sometimes sold as “okay” for 75–90 gallons, that is not suitable long‑term. A realistic minimum is 6 feet of length and at least 125 gallons, with 180+ gallons strongly preferred for adults. This species is an active, continuous grazer and will pace and show stress colors in cramped systems. Providing open swimming space, high flow, and lots of rock with grazing surfaces is critical to keeping them stable and reducing aggression.
My Lieutenant Tang is turning a blotchy brown/grey and losing its clean blue‑grey body color. Is this normal, and what conditions cause this color change?
Color shifting in Lieutenant Tangs is common and can be normal or stress‑related. They have a natural “mood” pattern and can darken or show mottling during sleep, feeding frenzies, or social displays. However, persistent dulling, blotchy browns, or a washed‑out look usually point to stress: poor water quality (elevated nitrate or phosphate), insufficient algae or greens in the diet, low oxygen/high CO2, bullying from tankmates, or chronic crowding. Check ammonia and nitrite (should be 0), keep nitrate under ~20 ppm, ensure strong aeration and flow, and provide a varied herbivorous diet (multiple algae sheets daily, spirulina‑based pellets, and veggie‑rich frozen foods). Once conditions improve, color usually returns over days to weeks.
How aggressive are Lieutenant Tangs toward other surgeonfish and similarly shaped species, and which tankmates are most and least compatible?
Lieutenant Tangs are mid‑range for aggression: usually calmer than Sohal or Clown Tangs, but often more assertive than Zebrasoma species once established. They are particularly combative with other Acanthurus tangs and fish of similar shape and feeding niche. In a 6‑foot tank, mixing them with other Acanthurus is risky; in 8‑foot or larger tanks it can work if added together as juveniles and in a small group to spread aggression. They tend to coexist better with Bristletooth tangs (Ctenochaetus) and sometimes with Zebrasoma in large systems, especially if the Lieutenant is not the last tang added. Avoid cramped tanks, adding new tangs after the Lieutenant is settled, and similar‑shaped fish like certain rabbitfish unless the system is big and heavily rock‑scaped. Always introduce more passive species and smaller tangs before the Lieutenant whenever possible.
My Lieutenant Tang constantly grazes but still looks thin around the spine. What specific diet and feeding schedule does this species need to maintain a healthy body weight?
Lieutenant Tangs are high‑metabolism herbivores that require frequent, algae‑rich feeding. A single daily feeding is inadequate. Aim for: (1) Nori or other marine seaweed clipped in the tank at least twice daily (green and red varieties, not flavored snack nori), (2) a staple of high‑quality herbivore pellets with spirulina and whole marine ingredients, fed 2–3 small portions over the day, and (3) supplemental frozen foods with a strong plant component (mysis plus spirulina, herbivore blends) a few times weekly. In heavily stocked tanks, the Lieutenant may be outcompeted; use multiple feeding points and ensure it actually gets its share. A healthy fish shows a gently rounded belly and no pronounced pinching along the dorsal area. If weight is not improving after diet changes, check for internal parasites and consider a medicated food in a separate system.
Are Lieutenant Tangs prone to ich and other external parasites, and what is the best practice for quarantining and introducing them to reduce disease outbreaks in reef tanks?
Like most Acanthurus tangs, Lieutenant Tangs are very prone to marine ich (Cryptocaryon), velvet (Amyloodinium), and flukes. Their thin slime coat and constant stress from capture and shipping make them high‑risk introductions. Best practice is to quarantine every new Lieutenant Tang in a separate, bare‑bottom tank for 4–6 weeks. During quarantine, prophylactic treatment with either copper (at a stable therapeutic level) or chloroquine phosphate is widely used against ich and velvet, combined with at least two rounds of praziquantel or prazipro for flukes. Keep strong aeration and excellent water quality, and provide PVC pipe or simple structures for security. Only move the fish into the display tank after it has been symptom‑free for several weeks and eating aggressively. Skipping quarantine with this species is one of the fastest ways to infect an entire reef system.
All listed sizes are approximate, not guaranteed, and may vary slightly.
Introduction to Saltwater Tangs
Tangs, also known as Surgeonfish, are active, fast-swimming herbivores known for their bold coloration, streamlined bodies, and role in controlling algae growth. Found in coral reefs worldwide, tangs require large aquariums with strong water flow to accommodate their constant movement and grazing habits. While peaceful toward most tankmates, tangs can be territorial and aggressive toward other tangs, particularly those of the same genus. They are best suited for well-established reef tanks with ample swimming space and hiding spots.
Care Requirements
Care Level: Moderate – Requires large tank Minimum Tank Size: 75 – 180+ gallons Smaller species (e.g., Kole Tang) – 75+ gallons Larger species (e.g., Achilles Tang, Blue Hippo Tang) – 125-180+ gallons Aquarium Setup: Requires open swimming areas, rockwork for hiding, and high water flow Tangs are strong swimmers that thrive in environments with high oxygen levels and strong filtration. They are prone to stress-related illnesses like Ich, making stable water parameters essential.
Diet & Nutrition
Tangs are herbivores that require a diet rich in plant-based foods for optimal health and vibrant coloration. Diet: Herbivorous – Prefers marine algae, seaweed, and plant-based foods
Recommended Foods:
Nori and seaweed sheets (offered daily) Spirulina-based flakes and pellets Blanched vegetables like zucchini and spinach Occasional protein-based foods like mysis shrimp for variety A nutrient-rich diet prevents nutritional deficiencies and lateral line erosion (HLLE), a common issue in tangs.
Lifespan & Growth Rate
Lifespan: 8-20+ years Growth Rate: Moderate to Fast – Many species reach 8-12 inches Tangs require long-term care and proper nutrition to reach their full lifespan and size.
Temperament & Compatibility
Temperament: Semi-Aggressive – Generally peaceful but territorial toward other tangs Reef Safe? Yes – Does not harm corals or invertebrates Tangs do well in reef aquariums and community tanks with: Clownfish Wrasses Angelfish Large gobies They may become aggressive toward other tangs, especially those with similar body shapes or coloration. Introducing multiple tangs at once in a large tank can help reduce aggression.
Common Challenges & Considerations
Prone to Marine Ich: Tangs are susceptible to Ich and other parasites, so quarantine before introducing to display tanks. Territorial Behavior: Can be aggressive toward new tangs, requiring careful introduction. Water Conditions Temperature: 74-80°F dKH (Alkalinity): 8-12 pH: 8.1-8.4 Specific Gravity: 1.020-1.025 Tangs thrive in high-quality reef conditions with strong filtration to support their active swimming habits.
Color Varieties & Popular Species
Tangs come in a wide range of colors and patterns, making them one of the most visually striking fish families in the hobby. Yellow Tang (Zebrasoma flavescens) – Bright yellow body, one of the most popular reef fish Blue Hippo Tang (Paracanthurus hepatus) – Electric blue body with black markings, also known as the "Dory" fish Kole Tang (Ctenochaetus strigosus) – Brownish body with blue highlights, a fantastic algae grazer Achilles Tang (Acanthurus achilles) – Black body with orange crescent tail, one of the most challenging tangs to keep
